1. Field of the Invention
The present invention relates to an electric element, a switching element, a memory element, a switching method and a memory method.
2. Description of the Related Art
Electronic memories commercially available contain respective bistable elements configured so as to be switched from a state of high resistance to a state of low resistance or from a state of low resistance to a state of high resistance when electric potential is applied to the electronic memories. Such an electronic memory as described above is usually called as a “resistance memory device”. In the resistance memory device, since the resistance of the resistance memory device is varied in accordance with an electric potential to be applied, data are allocated to the respective resistances and thus, stored so as to function as a memory element.
It is well known that chalcogenide materials, semiconductor materials, oxides, nitrides and organic materials can exhibit respective resistive memory properties. A resistive memory device containing the material as described above has some disadvantages of high operating voltage and current, poor resistance and poor handling of the material (which is utilized as a thin film). Recently, the disadvantages of the resistance memory device can be overcome through the drastic development of material engineering so that attention is paid to the resistance memory device as a multi-bit operating memory of nonvolatile, low electric power consumption and high density recording. As the resistance memory device can be exemplified a Phase Change RAM (PRAM), an organic memory and an Oxide Resistive RAM.
In the case of the organic memory as an example, an organic memory layer is formed between a top electrode and a bottom electrode and memory cells are arranged at the cross points of the top electrode and the bottom electrode. As a result, the organic memory is formed in matrix shape.
A typical resistive memory device has two resistance states of low resistance setting state and high resistance resetting state. Therefore, if data “1” is allotted to the low resistance state and data “0” is allotted to the high resistance state, two data logic state can be stored in the resistance memory device. The two states of low resistance state and high resistance state can be switched by applying a voltage or current to the resistive memory device. The voltage or current to be required to switch from one state (e.g., high resistance state) to the other state (e.g., low resistance state) is defined as a “switching window”.
At present, it is difficult for a metallic oxide resistance memory or an organic memory to ensure the switching window. With the organic memory, since the operating voltage fluctuation is large, it becomes much difficult to ensure the switching window.
In this way, in the resistive memory device, if the difference (i.e., switching window) between the voltage (or current) to induce the setting state and the voltage (or current) to induce the resetting state can not be ensured sufficiently, the operating reliability of the resistive memory device can not be realized. However, it is difficult for a conventional resistive memory device to ensure the switching window so as to lower the operating reliability of the resistive memory device.